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Simple Debouncer in Swift 4
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| // | |
| // Debouncer.swift | |
| // | |
| // Created by Sam Oakley on 20/03/2019. | |
| // | |
| import Foundation | |
| class Debouncer { | |
| private static var pendingRequestWorkItems: [AnyHashable: DispatchWorkItem] = [:] | |
| static func perform(context: AnyHashable, after: DispatchTimeInterval, block: @escaping () -> Void) { | |
| let pendingRequestWorkItem = pendingRequestWorkItems[context] | |
| pendingRequestWorkItem?.cancel() | |
| let requestWorkItem = DispatchWorkItem(block: block) | |
| pendingRequestWorkItems[context] = requestWorkItem | |
| DispatchQueue.main.asyncAfter(deadline: .now() + after, | |
| execute: requestWorkItem) | |
| } | |
| } |
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"Debouncing" is the process by, if there are multiple, rapid calls to a function, only the final one will actually be executed. The perfect example is a web search that happens as the user types - you want to avoid making a call for every character that is entered, but still fire the request without having to hit a "search" button. This way, once the
afterduration expires with no more calls, the block is run. Thecontextdefines the type of the action.